Electron switching means and circuit



y A. M. SKELIIETT 2,376,395

ELECTRON SWITCHING MEANS AND CIRCUIT Filed March 5, 1945 INPUT #1 INPUT #2 Qt L2 v77 /0 we III R/Z m3 BA m2 c4 CA 5 lNVE N TOR A. M. SKELLETT ATTORNEY Alli it M Skelle Theswimhing; rate is chqs er such that gthe ,traces 3 on the lumine si zae nt.t-screex-i are npeated at a? ne quenqy pqualj at least tq t hat required; fofwpeit switc l i i ng. qiijcl litjv including secondary emission type yapyum; tubes; or devices, for ,succgssively switching fmm on emto another of a plurality of, sig alsourcesfi Anothgr object, pr the ihvjiitiohj is in; $109165. t

a" switching 'circuit for successively switching 55 ter o n c d; thatg ln squa ELEdTRO'N swiufcmNG MEA tubss r'ir "d eyiceis embgdying e lsctrbii'ic pontaptg in switching circuits rgquirihg opening and 010's ity (in a p illustrative pircuit -apai oi 193016 sig alsprtransie tsi Theswitqhirji'g bjrcuit b prises" a, square wave generator o linultivibfator dishagge dyic birciiits, andthe ciib lit airi a ge' j nient may be based on that of Fig.*12'oftha t* patght. This generator constitutes a. sou

sec0nd,orm0r., U Each electronic switch may comprise r a;

tubes, one spurce'fbeing sq dgihhqtsdfthigiqh tht electronic gontact' ii iqng tube, and (the, {Qthlf o rcet mns ihes s iwit99 W? h sf;

suppliqd the; i ppt electrQt ies" .biif th primary section oone electrqn switch; gndtth e" pthei" squ rn n ed wav i up iedjto;thezinputje trodes-0f rthehlnnn aryet bri Qt"??? d he 'j cohstants, maybe of), desired magnitudeanq.t

mary section may thus be controlled or regulated alternately to establish and disestabli'sh secondary electron emission in the secondary electron section of the respective electron switch, the two electron switches operating in sequence by virtue of the 180 degree phase separation of the two control waves. The resultant alternate closingand-opening of ith' "electronic contacts? enables the alternateapplic'atiori to the cathoderay'tu'be of the signals from the sources under examina; tion, at a rate determined by the frequency of the 1 square-topped wave output of the -generator.

The additional grid in the secondary electron section of each electron switch constitutes an electrostatic shield between trigsec nqsry emitter and collector electrodes of the sec ran; The

-"nected to a suitable source of potential positive; .withrespect to the cathode and through resistors o f' appropriate proportions, and the electrode In is bombarded with primary electrons so as to establishsecondary electron flow between the elec- .daaesim, lljthe latter constitute in effect a low higher th frequency of switching between the two sources the smaller the capacitance that may. be,"

tolerated in the connection coupling the sources to the respective electronic contacts. The in herent capacity: oi the latter at or apov e a pa 1: ticular frequeny.. of operation might be of the, same order or ,oi greater magnitude 3 compared to such coupling capacitance. In the absence of the addit ion al grid,: there might v heior such conditiqns, transmission across the electronic, conct ven u in the paf fillet i r efs qq qer electron flow condition, or the electronic contact. g oren mn ete under anding f he x r zv n tion willbe obtained from the de ,r descripe mt at f ll ws ake nr e es wn h,;.. h single figurecf the ;accompanying;drawing,show? insa rc t ar n ment 4 11 irel t 3 19: venetian. v Y v The inrention. is illustrated as embodied in a wit h ng-c QfQr ;,a Qi% .1: h a aths ode raymtube ,CRT for enabling simu'ltaneousfex n mat o s ll i h re for 6f mmrz tl ity, for example a. pair or ,varia evsig nalsr The sources of these variable sign s a'reIindi ge- :1 s Input r 9; 1 d pl i .Q' 2 i h input terminals I; Landfil z oigthe'swi tchirig calculi-te t The cathode, ray, tube, may besoi. conventional pe ce n s h n ele t emw 'Q mcl'ctronun ll two pairspf electron ray or beam deflecting plates,5,=5 and B, 61, and including a n 'fenlar ged screen or target portion 1 coatedron its'jnnersurface with. suitable fluorescent Ior lulfni'nescent' material to .fprovide, .visual indication or; the. electron beam incident ther eon, 1 The plates .5, 5- may ,be connected to any suitable source. 8 'r of a sweep .or time-axis wave, and the .plaf 6,f 6"; are. connected through ,theswitching .circ' SC to the j sourcespf thejsignals totbe examined The s'witching circuit comprises a; plurality, of. l secondary electron emission type; va "um; tubes vTl;v:r2', 1v'-r3. Tlf1e,tubs ,VT! vrrz are Iafr'nodification of a, vacuumgtube electronic contact. nee, vice disclosed in my aforementionedpending an plication Serial No. 422 228, Eachl; tube l, VTI,

a ness" primary electromsection t and. a

secondaryv electron. section or electronic contact in an evacuated enclosure or, envelope; The lat: ter comprises Q. a plate electrode llll' a'nd; 9a. grid. electrode J l. The former (electrode Ill} istreated resistance contact and are adapted to transmit electricrsignals or.waves bidirectionally. In the 'absenceaof primary electron bombardment suflito the electrode l 0,; may 'lberre'gulated .1 to fclbse! or .tolfbDehiI'the electroniccontact} asIei-ipla in d e1 fi lif i li nfie l tion. a 'Each cathode.ISisc nnected to groundha d each' primary vanode .is' connected to}v wer i potential =-terrr'1inal ofQa carce BA; o f jdirectncur rent potential, for vexample a battery f'orl v, primary anodes and the Q electrodes of he elec troni'c,contacts, 'Ilieelectrodesnl l raretco nnec through resistors RH R'll f to'fthe high per al terminal orfsouf'1fce.,13s,. and theielectrodes I v connected to a terminal of, lower .poten a sourcelBA through ajcommo'riresiston R] I The. electrode 11 or tub V'Il is corinected..- g the terminals [,1 through a condenser'Cl. a dthc corresponding electrode of ,tube'IVTZ ;is conn ted through a'con'den'serfC2 to onetofitheteit inals 2, Each. elec,trode' I 0 is connected, through a; condensergjCi to. one of the pair of. .cathode'vray tube deflector platesj B, 67 for example plate .6, the other platebein gconnectedjto ground, and also to' ground through. a res tor R15, The in,- put grids'j I dare connected through resistors RI'Z; R12, an, my to the loyv'potent ialterminal on a Source CA' ,of' direct current biasing, potential, for example,,a battery, and through coiiplingcom 1 densers cq, C5 to, output terminalsflot the circuit, ofthe tube. Thegrid bias 'providedby the source'CA may be such that, thefprimary elecrq tron, flow to. the jprimary anode in each: tubeflvTl on one surface so as to emit secondary electrons I in .ratiogreater than unity.when bolnbardedrwith p im r i stmnsi pingi wi h-su able v loci y on the treatedtsurface ,The grid' electrode is in the path or ;such,pri mary. electrons to the elec; trade [m -and s adapted to 'L collec't secondary electrons mrtteany: electrode ,I ll... "The primary electron section 'comprises] a t primary. electron source br cathode I :I.3',I;' an; input icont'r ol grid Q! 4 VTZ'is insuff cient to establishthe secondary .elecfv, tron flow in the secondary electron. section. so, as y to close the ,electronic. contact, that is thejelec tron ic contacts IwouldQbe fope'nf Fona purpose to beexplainedmore fully,hereinaitegIeacht e" VT! VT2 includes a third j electrode p. l2 in its secondary electron section. Theelectrodelfi may be a grid and is interposed between the electrodes In H I land is connected to a terminalot the SQllice BA such that its potential is betweenthe po ten; tials at which the electrodes 10, l sten 'ated. The tube VT3 is of the ,type 'disclcse lf aforementioned Patent 2, 2Q3,l"77. It edge -sea primary electron section having 5 a primary e tronlsource or cathode l'lfl'ani nput t I8 and a'primary anode l9 contain 4 N ture 3ll forthe escape o f a portion o ew leq ens ach rima y flee-5 a.

-.mined, by the secondary electron section cornprisinga pair of auxiliary electrodes il' 22',fthe. e1ec'trode22 .being; a plate having asurfacetreatedto emit secondary electrons in ratio greater than" unity when bombarded with escaped primary electrons,

and the electrode 2| being a grid positioned in the path of escaped primary electrons to the electrode [22, and adapted to collect secondary. electrons emitted by the electrode ZZfjtand a defiectorelectrode or plate 20'Ytied to thecathocle and position'ed in the normal pathyof theescaped primary electrons to deflect. or bend the latter in' ajdire'ction to cause the escapedelectron to tubes" will be energized {alternatelm that is}; one

electronic contact will be closed while the other is open,and viceve'rsaJDuring the .time the res-pective; electronic contact is closed, signali wave from InputNo. 1 or'Input-No 2, 'asthe casemay be; will'be impressed on the cathode ray tube deflecting plates 6, 6"Ithr'ough'the condenser C1 or C2, the electronic contact ofitub or VTZ, and eosdenser C3' and resistorRli The elece tron ray or beam oi the cathodefraytube will be caused, -th'reforeyto trace alternately the waveforms of the signals, from thetwo sources.

' By causing the tubes VTI, VT2, to switch on and bombard theelectrcde 22", all'ofthe electrodes being b in a common evacuated enuelopeif control grid connected f to grounded cathcde through a resistor R5 and a source Cf cfdirect current biasing potential, and to the lctr'otie 22' througha condenser Clef. The secondary electron collector grid 2 l and the primary anode 19'? are connected through a resistor R7 w the high potential "terminal ofasource B" of direct e t p ential; the lbwpotential terminal jof which is connected to'the grounded cathode, and

the, secondary electron emitting electrode 22"is connected througnafresistor Bt toa point on the source "Bf at a potentiallower, than that of its associated resistors, condenserand potential sources constitute a .square wave generator or niultivibrator of the type disclosed and" described I in m Patent 2,293,177 witlibrefrence to Fig: 12.

some drawing" of. that patent, the correspondingfcomponents bf the square wave generator oi this disclosurefbearing the "same designations primed. By" suitable "selection of the circuit com s tantslthe instantaneous potential of the control gridil flj with reference to theicathodefmayube greaterthan that of thec'ou iing c. 99

caused to swing repetitiouslybetweenwide limits,

o whereby both primary electron, and. secondary electron flow in the tube vary abruptly between Widefihnitsbecause 0f he triggeractionflcfflthe tube; such that the" instantaneous potentials on the primary anode la and au i i rrai d f vary' abruptly but in' opposite directions. These I potential variations are. impressed on the input control grids M of the tubes VfI'LgVTZ, through the condensers C4, f C5, Tas square-topped .waves 180,.degrees out of phase; The frequency of. the waveswilljbe the same and of a iralueQdeter; constantslolithe fmultibrator circuit. i 1 qj In the operatiQnofithe circuit arrangement de-. scribed, thesources constituting lnputNoQl and and 2,: Z andthesquare wavegenerator will be continuously. supplying the squa e-topp control off at a sufficiently high rate, and aided by per sistence of visionf'the traces of the wave forms value the capacity of the coupling condensersC l',

CZmust lie decreased. If the switchingiate or frequency is. made sufficiently high, foiflexample, of theiorder' of" lO lO cyCles per second for more, a frequency will be reached'atwhichf the mag nitude of the interele-ctrcde capacit;y between the. secondary electron emitter electrode I 0 and its'associated collector gridl ,l in eachtube VfIj,

er Cl. C Zjrequired at that frequency; Undersuch-coi' dition, the electronic contact will not befopen TK durin absence .of secondary electron flow. be,-

tweenthefelectrodes constituting the contact, but

.willlprovide a capacitive path for thesignal wave.

The provision of the additional orjgrid electrode I 2 between 2 the electrodes constituting the. telectronio contact and maintaining such gridliat a direct current potential between thejoperatingor indicated, in. the absence of the control waves, the input grids H; are at a potential with respect to theircathodes such that the permitted primary electron flow is insumcient tpf QIIabIG'SBQ-r electronic contacts of the tubes. The decreasei'n the potential "difirence between the input grid and its associated cathodeduifin'g eaclrpositi ve half cycle ofQthebontrol, wave willbe suilicient .to permit such an increase in V the; primary electron flotv in the particular tube that secondary elec tron flow is established inthe secondary'electron section and the electronioconta'ct is elosedl During the other half .cycle oithecontrol lwave,"the tube will be restored "t'o' its' initial *condition. Sincethe controlwayes are 180 degrees out bf phase;the secondary'eledtron sectlons of the two ondaryjelectron emission in and closure "of the Working potentials of the contact electrodes corf rects for this condition byjintroducing eleetrostatic shield. between the, electrodes cf the electronic 1 contact, thereby reducing the j effectivecap'acity between theccntact. electrodes to ayaluesmall comparedlto thatofthe condenser.

Since the electronic ccn'tactsof the tubes VTI, VTh have bidirectional transmission properties upon establishment of secondaryfelectron;flow therein, it will be evidentto the skilledfin j'the art that if the cathode. ray tube "were. replaced by a suitable signal wave source and the signal sources connected to terminals l, l and'Z, 2. were replaced by suitable utilization o load circuits,

theswitchingcircuit 5C could be employed tosup:

ply such utilization circuits sequentially or lal .ternately. from a common orsinglesignal we've source, at a rate or irequencyygoverned by the square-topped wave generatorl Other circi it applications of the tubes V'IfL VT Z will readily occur to the skilled in the "artjthose specifically tion. What is claimed isi presently preferred embodiments iiiyen- 1. In combination, a pluralityof signaisoure s of varying-voltage, a common utilization circuit for the signals originating in said sources; asep'arate transmission path" onnectmg eecnsource to said'commcn circuit to supply energy o'f ithe source to the circuit, 'anelectroniccontact inea'ch path comp'risingfa pair of spaced electrodesfin evacuated enclosurer for chan in h i ficiency of the path with respect-to transmission of signalto saidcommon-circuitupon establishment of secondary electron flowbetween said electrodes, and means formomentarily establishing secondary electron flow betweenthe electrodes of each contact in sequence, whereby'signals are supplied sequentially from said source to said common circuit. r

2, In combination, a pair of signal sources of varying voltage, a common utilizationcircuit for the signals originating in said sources, a separate transmission path connecting each source to said common'circuit, an electronic contact in each path connected in serial relation to one of said sources and said circuit and comprising a; pair of spaced electrodes in an evacuated enclosure, for. closing the path for transmission of signal to said common circuit upon establishment of secondary electron flow between said electrodes, each of said pairs including a secondary electron emitting electrode and'a secondary electron collecting electrode, and means for'establishing secondary electron'flo'w between the electrodes of each contact in alternation, whereby signals are supplied alternately from said sources to said common circuit, said means comprising primary electron emitting means associated with said contacts to emit electrons "for bombarding said secondaryelectron emitting electrodes to produce electron emission therefrom, direct voltage supply means, means connectingsaid primary electron emitting'm'ea'nsto a: point on said direct voltage supply means, two separate impedanc'es to sign'al currents," one of said impedances' connecting a second point on said direct voltage supply'means of higher potential than said first point'to an electrode of one of saidpa'irs, and theotherof saiddnipedances connecting said second point to an electrode of the other pair, a common impedance to signal currents connectm the other electrode of each 'pair and said utilization circuit to a point on said direct voltage supply means of potential higher than that of said first point and difierent from that of said second point}; a separate control'grid for each electrode pair for controlling said primary electrons, means for fixing the potentials of said "control'grids. with respect to said first point, and means for changing said'potentials of "said control grids in the same sense alternately. f

3. In combination} a source'of variable signal, afitili'zationcircuin'a signal transmission path c'onnectihg'said source and circuit, a condenser and 'an electronic contact serially included in said path in serial relation to said'so'urc-e and said circuit, said electronic contact comprising a pair of spaced electrodes in'an evacuated} enclosure, the signal path between said electrodes being closed by establishment of secondary electron flowbetween said electrodes, the capacity offsaid condenser'and the capacity between said electrodes being of about the same order ofrnag'nitude, an electrostatic shield between said .electrodes to reduce the effective capacity between said electrodes to a value small compared to that of the condenser, and means to establish secondary electron flow between said electrodes intermittentlyat a high frequency, whereby signal from said sourceis supplied to said circuit intermittently at such frequency. Y r

4. Incombination, a pair of sources of variable signal, a common utilization circuit, a-signal transmission pathindividual to each source for connecting it withsaid commonicircuit; a condenser and an electronic contact serially included arraee in each of said-paths in; serial relation to its,-connected 1 source a'ndysaid common circuit, each electronic con-tact comprising a pair of spaced electrodes-in an evacuated enclosure, the 5 signal path between said electrodes being closedby establishment of secondary electron flow between said electrodes, the capacity of the-condenser in each path and thatbe'tween theelectrodels-ofthe electronic contact in the' same ;path-' being of about the same order of magnitude, an electrostatic shield between the electrodes of each [elec: tronic contact to reduce the eifective capacity be: tween its electrodes to a value small compared to that of its'associated condenser, and means to establish secondary electron flow ,between' the electrodes of the respective electronic contacts said impedances being connected between"said shield and one of said electrodes, andsaidlojthfer impedance being connected between said shield and said other electrode, and means maintaining the electrodes at different potentialspositiv' with respect to said source and maintaining weav agepotential of the shield at a Value between the Working potentials of the electrodes.

6.' A switching circuit for interconnecting a plurality of signal wave circuits, comprisingia' signal wave transmission path cor'n' ecting one of'said circuits and a second of said circuits to supply signal energyof one'to the other, a secondsignal wave transmission path'connecting a, third-of saidcircultsand said second-mentioned circuit to supply signal energy of one to the other eac h of said'paths including an electronic cont'actcom; prising a pair of spaced electrodes in'an evacuated enclosure, the signal path between gamete;- trodes being cl'osed for bidirectional transmission therethrough' upon establishment of secondary electron flow between said electrodes, ad'ir'ect current path from one electrode of'ea'ch pair 'to the other electrode of the pair with meansffor producing direct Voltage included in each'orsaid two direct current paths, and means to establish secondary electron flow 'in" said contacts"alternately' at a selected frequency, whereby said transmission paths are closed alternately for signal wave transmission between said" first-men'- tioned and third mentionedcircuits and said second-mentionedcircuit. i

7. A wave translatingsystemcomprising an electronic device having a' primary electronsection including an electrode and a" secondary electron section including two other electrodes, a source of voltage waves coupled to said first-men; tiQned-electrode and one of said twoelectrodes; a load circuit coupled to said first-mentioned elec trode'and the other of said two electrodes," an electrostatic shield interposed between said'two electrodes; anda connection of low impedance to high frequency between said shield and said first,- mentioned electrode.

8.. A wave translating system comprising a source of voltage waves, a loadcircuit, a coupling circuitfor coupling said source and said mmencuit including a secondary electron emitter and a secondary electron collector having a secondary electron discharge path therebetween for controlling the transmission efilciency of said coupling circuit, 'an electrostatic shield between said emitter and said-collector, means comprising a source 7 of primary electrons for producing a stream of electrons bombarding said emitter, means producing variations of said electron stream that vary the impedance of said discharge path with 10 such rapidity that in the absence of said shield the interelectrode capacity of said emitter and shield and a point on said direct voltage supply means at a potential between the potentials of the two first-mentioned points.

a ALBERT M. SKELIETT, 

